3-D for Your Ears: Building Dolby’s Atmos System for Brave

Arrays of speakers hang from trusses on the ceiling of the Dolby Theatre in Los Angeles for the Brave premiere.Photo courtesy Dolby Laboratories

SAN FRANCISCO — A theater in a bustling multiplex seemed like the last place to find a secret laboratory.

For seven months, Room 10, a theater on the top floor of the AMC Van Ness 14, was closed off to the public. Inside, engineers from Dolby Laboratories were testing a new surround sound technology called Atmos, rushing to get the sophisticated system done in time for the premiere of the Pixar movie Brave.

“They basically had trusswork everywhere so they could try hanging speakers in every possible location,” said Will Files, a sound designer at Skywalker Sound who worked on the Atmos test mix for Brave. Speakers were everywhere — hung in arrays on the ceiling, lining the walls.

A few blocks away, at Dolby’s headquarters, researchers furiously wrote lines of C++ for the Atmos rendering engine, compiling and uploading it to be tested in real time in the secret theater.

The goal: To accurately simulate the sound of a helicopter roaring overhead, or birds chirping in the lush canopy of an Amazon rainforest. A killer stalking his prey, with his footsteps on the ceiling. Or — for Brave, an uplifting medieval fantasy tale set in the Scottish highlands — to simulate arrows whizzing by, horses galloping away and bears stomping through the forest.

“Sound is 50 percent of the movie-going experience,” as George Lucas once said. With the massive resurgence of interest in 3-D movies over the past several years, sound needed to become more 3-D, too. But 3-D visual effects — often tacked on digitally in post-production instead of being well thought out from the very beginning — started seeming gimmicky and predictable.

“The thing about 3-D visuals is that it’s not how we actually see in 3-D; it’s sort of a rough approximation,” Files said. “I think the difference with Atmos is it’s much closer to how we hear in 3-D. You don’t need special glasses; you don’t need headphones. It’s not as much of a jump. It’s not as faux.”

To entice audiences to drop $15 to see a movie at a major multiplex instead of on a laptop, theaters need to provide a premium experience drastically different from what a consumer can experience at home. Building a richer, more-enveloping surround sound experience with upward of 64 speakers — and placing arrays of speakers directly above viewers’ heads, where they generally never have been before — seemed like the way forward.

How Atmos Works

The concept of 3-D movies and surround sound are both old ideas, dating back to the first half of the 20th century. Walt Disney’s 1940 classic Fantasia was designed to have surround sound.

Many companies have worked in the field of surround sound in the 70-odd years since, but few have approached the ubiquity and market share of Dolby. By the early 1990s, Dolby’s 5.1 — six channels of sound (five speakers, plus the “.1” for a subwoofer) — became the movie industry standard. The technology became so ubiquitous that it infiltrated the consumer level, too; you could buy a Dolby Digital-equipped receiver and speakers at your local Best Buy, and build a serviceable home theater in your living room, and “5.1 sound” soon became a household word.

The sequel to 5.1 was 7.1, introduced in theaters in 2010 with the Pixar movie Toy Story 3. But 7.1 — eight channels, including the subwoofer — was an incremental improvement, not a paradigm shift. With two additional speakers in the surround, movies sounded better, more lifelike. But a movie mixed for 7.1 could only play that way in a 7.1-equipped movie theater.

Atmos was designed to change that, providing a platform that would work with a variety of theater sound systems.

Dolby rushed to finish the Atmos sound system in time for the premiere of Brave.Image courtesy Disney/Pixar

“We needed a format that was independent of the number of channels,” said Nicolas Tsingos, a computer scientist and senior platform manager at Dolby, in an interview with Wired. “The difference is, instead of carrying everything in terms of a fixed number of channels, we’re basically carrying individual sound effects.”

These individual sounds — like the debris hurling out of an explosion, or a voice booming ominously from the sky — are mapped to “objects,” which can be controlled dynamically and manipulated around the theater. There are two sides to the system — the rendering tool in the theater, and the tool that’s provided to the sound mixer, to create the objects and tag them with metadata.

“The rendering tool basically selects the most appropriate set of speakers, and plays the sound from those speakers,” Tsingos said. “So as the sound moves throughout the theater, the rendering tool basically blends between different speakers, so you can hear the sound gliding along the walls, for instance.”

The Atmos system does the math to figure out how to make it work best in every theater it plays in. “That’s the big conceptual difference with this system — we’re getting away from the idea of putting a sound into one specific speaker, and getting more into the idea of putting it into a specific point in space,” Files said.

Atmos took 5 years to build, in part because it wasn’t just about building the object-based system, but getting it to sound good in a theater. “There are a lot of algorithms that exist only to make the soundtrack sound good,” said Tsingos. “If you have small speakers you can actually redirect the bass to subwoofers…. There’s a lot more than the surround aspect, the spatial aspect. There are also a lot of core sound-quality algorithms in there.”

In a sense, the system resembles the way audio works in a videogame, said Tsingos. “Videogames have been using sound objects like this for a long time, because you have to render all the sound effects basically dynamically. Because the player, the character in the game, can move anywhere.”

A drastically more immersive surround sound experience is gaining industry traction — especially in China, which is expected to double its number of movie theaters by 2015. China’s Dalian Wanda group announced a deal last month to take over the U.S. AMC Entertainment Group for $2.6 billion.

“China is building — I think the statistic is around two to three auditoriums a day being built out there,” said Stuart Bowling, a senior technical marketing manager at Dolby, in an interview with Wired. “It’s got the biggest growth of any geographical region in the world…. You have companies like China Film Group, who has an amazing facility out in Beijing. It’s huge. Warner Bros. has what people consider to be one of the largest lots in the world, and China Film Group is even bigger…. They’re very interested in the technology, and they’re looking toward the end of the year to have an internal feature film release use Atmos.”

Four major films over the next year are expected to feature Atmos, according to Bowling. If speculation on numerous websites is true, Peter Jackson’s The Hobbit will use the Atmos system.

Brave With Atmos

While researching this story, I watched Brave twice — once in a regular theater and once at the AMC Van Ness, one of 14 theaters in the United States currently set up to run Atmos. With Atmos, Brave was a substantially better movie. The mix was a hybrid — about 75 percent was in Dolby 7.1, a mix helmed by Skywalker Sound’s Gary Rydstrom, with about 25 percent subtly separated out into Atmos by Files.

The difference was palpable.

(Spoiler alert: Minor plot points follow.)

Atmos helps flesh out the relationships among Brave’s Queen Elinor, King Fergus, Merida and the triplets (Harris, Hubert and Hamish).Image courtesy Disney/Pixar

The dramatic tension in Brave between feisty female heroine Merida and her prim mother, Queen Elinor, felt more convincing. Elinor’s transformation into a bear mid-movie was more sudden and horrifying. And Merida and Elinor’s reconciliation by the end of the film came as less of a predictable happy ending; it felt more genuine and heartwarming.

When there was emotional distance between Merida and her mother, Files put their voices into objects, pointing the voices to separate speakers. Merida and her mother weren’t just separated visually on-screen; they were separated sonically, too.

“In the system, we separate them slightly so Mom comes from the speaker in the left side of the screen,” Files said. “Merida comes from the right side of the screen … putting some distance between them, physically and emotionally.”

Meanwhile, the Queen and her adoring, bumbling husband, King Fergus, were always in the same speaker, subtly underlining the closeness between them.

In a key scene in the movie, set at the dinner table in the castle, Elinor informs Merida that she has to get married. Merida is having none of it. Under the huge wooden table, three little triplets — who are mainly in the movie for comic relief — frantically munch dessert.

“One of my favorite parts of the mix is when you go under the table in that scene — down under the table with the triplets, and they’re eating cookies,” Files said. “We took Dad’s voice and put it on the ceiling…. It helps tell the story of what it feels like to be these little boys under the table, and have this big, giant dad up above them, booming down.”

When Queen Elinor morphs into a giant bear, Atmos made her seem more gigantic and terrifying. Files sent the bear’s voice to an overhead speaker, so that the creature seemed to literally tower above the audience. Merida’s voice, meanwhile, was pointed to a speaker far below the bear’s voice, making her appear dramatically smaller.

Then, in the dramatic finale, when Merida and her mother reconcile, their voices are joined in the same speaker.

It was a bit of sonic sleight of hand, but it worked wonders to imbue Brave with unexpected emotional depth. Pixar’s visual fireworks dominated the screen, but the sound had subtly become the star of the show.

“What we want the audience to do is to not think about the sound,” said Skywalker Sound’s Files. “We want it to be subtle. That’s when sound operates most effectively on the audience.”

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